Multicenter studies including the Women's Health Initiative have demonstrated increased risks of stroke, breast cancer and heart disease in older women taking hormone replacement therapy. These concerns have led women to seek alternatives for the relief of menopausal symptoms such as using botanical dietary supplements. For example, black cohosh and red clover are being used by women for the management of menopausal symptoms and rank 7th and 18th, respectively, in sales among all botanical dietary supplements in the United States. The safety of women using botanical dietary supplements is of such importance that this will be the focus of the preclinical and clinical studies in Project 3. Since efficacy is also important, the efficacy of black cohosh for the prevention of osteoporosis will be evaluated in women as part of this project. We hypothesize that most botanical dietary supplements used by women to manage menopausal S3miptoms are safe, but some botanicals might pose risks in terms of interactions with therapeutic agents or through the formation of electrophilic metabolites. To test this hypothesis, the top 17 botanical dietary supplements used by menopausal women will be investigated for metabolic activation to potentially toxic metabolites, and the potential of these botanicals to cause drug-botanical interactions will be studied in vitro for all 17 botanicals. A randomized, placebo-controlled clinical trial of botanical-drug interactions will be carried out in post-menopausal women using three botanically authenticated and chemically and biologically standardized botanical dietary supplements consisting of black cohosh (Cimicifuga racemosa), red clover (Trifolium pratense) and hops (Humulus lupulus). Finally, the efficacy of black cohosh for preventing osteoporosis in post-menopausal women will be investigated through post analyses of specimens from our recently completed 12-month clinical trial of safety and the prevention of hot flashes. Through these studies, the safety and efficacy of botanical dietary supplements used by menopausal and post-menopausal women will be evaluated. These in vitro and in vivo studies will produce preclinical and clinical data that wifl advance the understanding of botanical-drug interactions and help determine the potential efficacy of black cohosh for preventing osteoporosis in women.